WesWorld

The RSAN Ringhorn has 4 triple 5" turrents on a ship 4' thinner and 70' shorter. So everything should fit, it wont make a confortable boat but it'll fit.

Personaly I would go with the 12x4.7" version with thicker deck and no belt armor, but the custumer comes first.

There is a big difference between the two designs, especially when it comes to internal space...

Ringhorn
Armament: 117 tons
Machinery: 399 tons
Fuel, Ammo, Stores: 301 tons
Misc: 0 tons
Coverage needed: 101.2% of 62% of 115m/248.36ft
Coverage in picture: 70.9m/232.6ft
Coverage in sim: 75.7m/248.4ft
Off by: 4.8m/15.7ft

DDX-1
Armament: 101 tons
Machinery: 1096 tons
Fuel, Ammo, Stores: 585 tons
Misc: 50 tons
Coverage needed: 131.6% of 62% of 450ft/137.16m
Coverage in picture: 271ft/82.6m
Coverage in sim: 390ft/118.9m
Off by: 119ft/36,3m

Did you try and see how much coverage 390 feet is in your picture? Believe me. It's a lot!
(rough guess would be from the stem to where the shafts exit the ship, probably even further back)